Ex-Smokers Who Re-Start Show Greatest Lung Damage
STOCKHOLM (Reuters Health) - Smokers who kick the habit and then start up again could have a greater decline in lung function than smokers who never quit, according to Swedish researchers.
This must not, however, be interpreted to mean that smokers should abandon attempts to quit. On the contrary, said Dr. Bo Lundback, lead author of the study and an associate professor in respiratory medicine at the National Institute for Working Life in Stockholm.
``All smokers must try to stop smoking. If you succeed, then do not start up again,'' Lundback emphasized.
His report is part of a larger, ongoing research program including 40,000 people, called the Obstructive Lung Disease in Northern Sweden Studies (OLIN). The current findings were presented last week at the 11th Annual European Respiratory Society Congress in Berlin.
In the 10-year study, Lundback and colleagues analyzed lung function and smoking habits among 1,116 men and women aged 35 to 68.
Participants were divided into five groups: those who never smoked; those who stopped smoking 10 years before the study's start; those who stopped smoking during the 10-year observation period; ex-smokers who re-started during the observation period; and those who smoked throughout. The study did not include those smokers who ``took breaks'' for less than a year.
After 10 years, non-smokers showed the smallest annual decline of lung function, as measured by tests of how well they could forcibly expel air after taking a breath, Lundback told Reuters Health.
Among smokers, those who re-started after at least one year of abstinence showed the greatest annual decline in lung function--even slightly higher than people who smoked throughout the 10 years.
``What ex-smokers lose in lung function, they'll never get back. The part of the lung they can use will be smaller,'' Lundback said. ``And, within the first couple years after ex-smokers re-started, the decline (in lung function) was much greater.''
It is still unclear how many years this rapid decline in lung function might continue and whether the lung function then stabilizes to the level of smokers who never quit, but Lundback and his fellow researchers are now analyzing that data.
He speculated that the reason for the rapid decline in lung function among ex-smokers who re-start could be that they have lost a defense in the lungs against smoke ``pollution''--a defense that was built up while smoking to protect against the ''constant attack'' on the lungs. When people stop smoking the source of pollution ceases, and perhaps so does the defense, leaving the lungs more vulnerable if they start smoking again.
One other study, from Arizona in the mid-1990s, had previously shown that ex-smokers who start again experience a faster decline in lung function than those smokers who never quit.
``Maybe there's something behind this,'' Lundback said, noting that the total number of cigarettes a person smokes is directly related to how much the lungs are damaged.
``The message,'' he said, ``is don't smoke.''